In technologies involving heat transfer, to improve cooling efficiency, dimples or other concave features may be added to fluid flow surfaces, such as within a turbine engine. Dimples promote turbulent mixing in the flow, specifically in the near wall region where boundary layer development can act to restrict heat transfer. The turbulence created causes mixing of the fluid which increases convective heat transfer efficiency within the system. Simultaneously, little loss in dynamic energy is realized.
Examples of large scale machineries with hot components that could benefit from improved cooling are turbine blades in the case of a turbine engine or the stator of a large-scale power generator. By increasing the thermal efficiency of the system, more heat can be removed by the cooling fluid flow which will decrease the temperatures of cooled components. Decreased component temperatures allow for longer component life and reduced wear on the components. An increase in cooling efficiency will translate into a cost savings by increasing component life and improving power output for specific fuel consumption.
Generally, the shape of the dimple governs the flow physics that promote turbulent mixing within the flow. A variety of shapes of dimples are known, including spherical (symmetric) and some asymmetric shapes. In general, these features have a strong correlation between improved heat transfer performance and increased pressure loss through the cooling channel. As a result, known dimple shapes generally all lack the ability to significantly augment the flow to increase heat transfer efficiency without substantial loss in flow potential.